We have developed a noninvasive method to measure sequential left ventricular performance following cardiac surgery in man. Radiopaque tantalum markers are implanted in selected locations in the midwall of the left and right ventricular myocardium at the time of surgery and subsequently visualized in radiograms stored in a video disc recorder. A light-pen/minicomputer system is used to determine the coordinates of the markers from the video monitor on a frame-by-frame basis, and these data are processed by a digital computer to obtain measurements of ventricular dynamics. The method provides, in essence, a "noninvasive cineventriculogram" which can be obtained and analyzed by a computer as often as desired after cardiac surgery without risk or discomfort to the patient. We have used this method for the past five years in extensive studies of the effects of cardiac surgery and physiological and pharmacological interventions on left and right ventricular performance. The proposed clinical studies examine right and left ventricular function and compliance in the immediate postoperative period, and the effects of specific therapeutic interventions. The ability to measure serially and noninvasively right ventricular dimensions after surgery permits unique studies in patients with pulmonary hypertension, right ventricular failure, and tricuspid regurgitation. The ability to measure intramyocardial dynamics in the distribution of coronary artery bypass grafts allows new studies in the efficacy of myocardial revascularization. The ability to perform serial noninvasive ventriculograms permits assessment of the chronic effects of newer oral cardioactive drugs. The availability of patients with both innervated and denervated (transplanted) hearts permits unique studies in cardiac physiology.